Technical Field
The present invention relates to a sheet manufacturing apparatus, a sheet manufacturing method, and a sheet.
Related Art
Making a sheet or film-shaped forming by accumulating a fibrous substance and causing a binding force to act between the fibers of the accumulated fibrous substance is an old technology. A typical example of this technology is manufacture of paper by a pulp papermaking (paper forming) process that uses water. The paper manufactured by the pulp papermaking process is usually a paper that has a structure in which, for example, cellulose fibers derived from wood or the like are intertwined and are partly bonded to one another by a binder (a paper strength additive (starch paste, a water-soluble resin, etc.)).
However, the pulp papermaking, which is a wet method, requires use of a large amount of water and makes it necessary to perform steps of dehydration, desiccation, etc. after paper is formed, so that very large amounts of energy and time are consumed. Furthermore, the used water needs to be appropriately treated as waste water. Therefore, the pulp papermaking process increasingly finds it hard to meet recent requirements of energy saving, environmental protection, etc. Furthermore, apparatuses for use for the pulp papermaking often need large-size utilities for water, electric power, waste water, etc., and therefore are difficult to be miniaturized. In view of these circumstances, it is hoped that a method termed dry method which uses no or little water will be developed as a manufacturing method for paper that replaces the pulp papermaking.
JP-A-2002-144305 discloses a waste paper board obtained by laminating a resin impregnated sheet on a layer-shaped forming obtained by defibrating waste paper in a dry manner and mixing the defibrated material with an adhesive and then subjecting the laminate to heat and pressure.
Some paper sheets or the like are provided with perforations, perforated lines, etc. for the purpose of, for example, making it easy to neatly tear the paper sheets without using scissors or the like or folding the paper sheets at predetermined positions. Such perforations and the like in a paper are often formed subsequently to manufacture of the paper by using another machine apparatus or formed in an added process for forming the perforations within the paper manufacturing process. Circumstances for the need for a machinery arrangement or a process for forming perforations in a paper or the like do not vary regardless of whether the paper is manufactured by the pulp papermaking or by a dry method as mentioned above in conjunction with JP-A-2002-144305.
Furthermore, in order to make it easy to tear (divide) a sheet without using scissors or the like or fold a sheet at a predetermined position, it is not necessarily considered necessary to form perforations or a perforated line.